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1

Grossmann, Steffen. "Statistics of optimal sequence alignments". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968907466.

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2

Starrett, Dean. "Optimal Alignment of Multiple Sequence Alignments". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194840.

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An essential tool in biology is the alignment of multiple sequences. Biologists use multiple sequence alignments for tasks such as predicting protein structure and function, reconstructing phylogenetic trees, and finding motifs. Constructing high-quality multiple alignments is computationally hard, both in theory and in practice, and is typically done using heuristic methods. The majority of state-of-the-art multiple alignment programs employ a form and polish strategy, where in the construction phase, an initial multiple alignment is formed by progressively merging smaller alignments, starting with single sequences. Then in a local-search phase, the resulting alignment is polished by repeatedly splitting it into smaller alignments and re-merging. This merging of alignments, the basic computational problem in the construction and local-search phases of the best multiple alignment heuristics, is called the Aligning Alignments Problem. Under the sum-of-pairs objective for scoring multiple alignments, this problem may seem to be a simple extension of two-sequence alignment. It is proven here, however, that with affine gap costs (which are recognized as necessary to get biologically-informative alignments) the problem is NP-complete when gaps are counted exactly. Interestingly, this form of multiple alignment is polynomial-time solvable when we relax the exact count, showing that exact gap counts themselves are inherently hard in multiple sequence alignment. Unlike general multiple alignment however, we show that Aligning Alignments with affine gap costs and exact counts is tractable in practice, by demonstrating an effective algorithm and a fast implementation. Our software AlignAlign is both time- and space-efficient on biological data. Computational experiments on biological data show instances derived from standard benchmark suites can be optimally aligned with surprising efficiency, and experiments on simulated data show the time and space both scale well.
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3

Amara-Korba, Enwer. "Optimal sequence and heat integration for multicomponent distillation trains". Thesis, University of Sheffield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340894.

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4

Mora, Castro Andrés Felipe. "Optimal switching sequence model predictive control for power electronics". Tesis, Universidad de Chile, 2019. http://repositorio.uchile.cl/handle/2250/170522.

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Tesis para optar al grado de Doctor en Ingeniería Eléctrica
En este proyecto de tesis, se propone una estrategia de control predictivo (MPC, por sus siglas en inglés) basada en el concepto de secuencia de conmutación óptima (OSS) recientemente introducido para convertidores de punto neutro enclavado de tres niveles (3L-NPC) conectados a la red eléctrica. La metodología de control propuesta, llamada OSS-MPC en cascada (C-OSS-MPC), considera explícitamente el modulador en su formulación junto con el modelo del sistema. Como se verificó a lo largo de esta tesis, la estrategia C-OSS-MPC está formulada para el control de la corriente o el control directo de la potencia activa/reactiva como variables primarias de control, mientras que el problema del equilibrio de voltaje del enlace CC se resuelve sin utilizar factores de ponderación en un bucle de control interno basado en una novedosa y sencilla estrategia de control MPC. Por lo tanto, la metodología de control propuesta controla de manera óptima tanto el objetivo de control primario como los voltajes de los condensadores de este convertidor de potencia. Bajo esta perspectiva, la dificultad de diseñar el factor de ponderación se evita en este trabajo y el rendimiento del sistema controlado no se ve afectado por un punto de operación particular del convertidor conectado a la red. La estrategia MPC resultante permite operar el convertidor con un espectro armónico predefinido, frecuencia de conmutación fija y una respuesta dinámica rápida y robusta en todo el rango operativo del convertidor de potencia, superando las estrategias MPC existentes en la literatura para los convertidores de potencia. Además, se ha propuesto un nuevo y eficiente algoritmo de optimización para encontrar rápidamente la solución óptima con el fin de hacer posible una implementación en tiempo real de la estrategia de control propuesta. Finalmente, se proporcionan resultados experimentales y de simulación para demostrar la efectividad y el rendimiento de alta calidad de la estrategia de control propuesta, lo que hace que este enfoque de control no solo sea adecuado para las aplicaciones de convertidor de potencia conectado a la red, sino que también para accionamientos eléctricos de alta potencia.
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5

Fischer, Jörg [Verfasser]. "Optimal Sequence-Based Control of Networked Linear Systems / Jörg Fischer". Karlsruhe : KIT Scientific Publishing, 2015. http://www.ksp.kit.edu.

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6

Islas, Anguiano Jose Angel. "Optimal Strategies for Stopping Near the Top of a Sequence". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822812/.

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In Chapter 1 the classical secretary problem is introduced. Chapters 2 and 3 are variations of this problem. Chapter 2, discusses the problem of maximizing the probability of stopping with one of the two highest values in a Bernoulli random walk with arbitrary parameter p and finite time horizon n. The optimal strategy (continue or stop) depends on a sequence of threshold values (critical probabilities) which has an oscillating pattern. Several properties of this sequence have been proved by Dr. Allaart. Further properties have been recently proved. In Chapter 3, a gambler will observe a finite sequence of continuous random variables. After he observes a value he must decide to stop or continue taking observations. He can play two different games A) Win at the maximum or B) Win within a proportion of the maximum. In the first section the sequence to be observed is independent. It is shown that for each n>1, theoptimal win probability in game A is bounded below by (1-1/n)^{n-1}. It is accomplished by reducing the problem to that of choosing the maximum of a special sequence of two-valued random variables and applying the sum-the-odds theorem of Bruss (2000). Secondly, it is assumed the sequence is i.i.d. The best lower bounds are provided for the winning probabilities in game B given any continuous distribution. These bounds are the optimal win probabilities of a game A which was examined by Gilbert and Mosteller (1966).
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7

Nagendra, Somanath. "Optimal stacking sequence design of stiffened composite panels with cutouts". Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170635/.

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8

Germain, Florence. "Estimation du mouvement dans une sequence d'images, en contexte lineaire optimal". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0030.

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La perception du mouvement dans une sequence d'images est un element cle de la comprehension d'une scene dynamique. L'information de mouvement est partiellement observable grace aux variations spatio-temporelles de l'intensite lumineuse. Le caractere partiel de cette observation, ainsi que la presence de frontieres de mouvement, constituent deux des principales difficultes majeures liees a l'estimation du champ des vitesses. Dans la grande majorite des approches existantes, la fusion des observations est effectuee spatialement, a un instant donne. Le plus souvent, le champ de vecteurs estime est alors seulement reconduit d'un instant a l'autre. Peu de travaux exploitent la demarche duale, consistant a fusionner temporellement l'information observable. Cette demarche, particulierement seduisante en ce qu'elle permet d'assimiler le probleme des frontieres de mouvement a la detection d'instationnarites fortes sur l'etat d'un systeme dynamique, constitue la base de notre approche. Nous proposons un estimateur sequentiel du mouvement image, base sur le filtre de kalman. Le vecteur vitesse image est estime independamment en chacun des pixels de l'image, en fonction du temps. La detection des frontieres de mouvement repose sur une analyse en ligne des statistiques du signal d'innovation. Cette approche est reprise dans le cas ou l'on ne dispose que de deux images. On derive alors un estimateur recursif, obtenu par approximation de l'estimateur recursif optimal, possedant de bonnes proprietes de convergence et de stabilite. Le comportement assymptotique de l'un et l'autre de ces estimateurs est evalue sur la base de sequences de synthese et de sequences reelles. Dans le cas d'un deplacement de faible amplitude, la nature lineaire de l'observation garantit l'optimalite de l'estimation par le filtre de kalman. Afin d'etendre l'estimation au cas des grands deplacements, caracterises par une observation non lineaire, on definit une variante sous-optimale a iterations locales du filtre de kalman etendu. On retrouve la une formulation en contexte optimal de l'approche multi-resolution de type descendant, classique en vision par ordinateur
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9

Hunziker, Angela. "Improving multiple sequence alignments using information from libraries of optimal pairwise alignments /". Zürich : ETH, Eidgenössische Technische Hochschule Zürich, [Departement für Informatik, Institut für Wissenschaftliches Rechnen], 2003. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=117.

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10

Luong, Dung Viet Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. "Optimal training sequence design for MIMO-OFDM in spatially correlated fading environments". Awarded by:University of New South Wales. Electrical Engineering & Telecommunications, 2009. http://handle.unsw.edu.au/1959.4/44513.

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Multiple Input Multiple Output with Orthogonal Frequency Division Multiplexing (MIMOOFDM) has been widely adopted as one of the most promising air interface solutions for future broadband wireless communication systems due to its high rate transmission capability and robustness against multipath fading. However, these MIMO-OFDM advantages cannot be achieved unless the channel state information (CSI) can be obtained accurately and promptly at the receiver to assist coherent detection of data symbols. Channel estimation and training sequence design are, therefore, still open challenges of great interest. In this work, we investigate the Linear Minimum Mean Square Error (LMMSE) channel estimation and design nearly optimal training sequences for MIMO-OFDM systems in spatially correlated fading. We, first, review the LMMSE channel estimation model for MIMO-OFDM in spatially correlated fading channels. We, then, derive a tight theoretical lower bound of the channel estimation Mean Square Error (MSE). By exploiting the information on channel correlation matrices which is available at the transmitter, we design a practical and nearly optimal training sequence for MIMO-OFDM systems . The optimal transmit power allocation for training sequences is found using the Iterative Bisection Procedure (IBP). We also propose an approximate transmit power allocation algorithm which is computationally more efficient than the IBP while maintaining a similar MSE performance. The proposed training sequence design method is also applied to MIMO-OFDM systems where Cyclic Prefixing OFDM (CP-OFDM) is replaced by Zero Padding OFDM - OverLap-Add method (ZP-OFDM-OLA). The simulation results show that the performance of the proposed training sequence is superior to that of all existing training sequences and almost achieves the MSE theoretical lower bound.
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11

Ejenstam, Joakim. "Implementing a Time Optimal Task Sequence For Robot Assembly Using Constraint Programming". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229581.

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Assembly lines in a lean production environment may persist for months or years, but due to the rapid change in demands on the consumer market they can be subject to quick changes. Robots have been proved to handle tasks that previously were limited to human workers: this is the goal of the flexible two armed robot developed by ABB. When installing a new robot into an assembly line there are several parameters which make it a difficult job for programmers, even experienced ones, to install the robot. These problems lead to long installation processes that can take weeks, and there are great benefits of automating the process of finding good solutions to the problem. In this thesis a constraint programming approach is presented as a way to solve the complex sequencing problem when installing a two armed robot into a new environment. When benchmarked against a reference case study, the implemented prototype  solutions showed an improvement of 17%, all within a time limit of 20 minutes instead of weeks. This shows that constraint programming can be a good tool for automating robot installations.
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12

Hirschi, Joseph Christian. "A Dynamic Programming Approach to Identifying Optimal Mining Sequences for Continuous Miner Coal Production Systems". OpenSIUC, 2012. https://opensiuc.lib.siu.edu/dissertations/542.

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Underground mines are the source of 33% of US coal production and 60% of worldwide coal production. Room-and-pillar mining with continuous miners has been the most common production system used in these mines since the 1960s. The introduction of continuous miners mechanized the underground coal mining industry triggering a period of sustained growth in mine productivity; however, productivity peaked at the turn of the century and has been in decline for a decade. Research on productivity in underground coal mines began at Southern Illinois University Carbondale in 2000 and led to development of a deterministic spreadsheet model for evaluating continuous miner production systems. As with other production models, this model uses a heuristic approach to define the fundamental input parameter known as a cut sequence. This dissertation presents a dynamic programming algorithm to supplant that trial-and-error practice of determining and evaluating room-and-pillar mining sequences. Dynamic programming has been used in mining to optimize multi-stage processes where production parameters are stage-specific; however, this is the inaugural attempt at considering parameters that are specific to paths between stages. The objective of the algorithm is to maximize continuous miner utilization for true production when coal is actually being loaded into haulage units. This is accomplished with an optimal value function designed to minimize cut-cycle time. In addition to loading time, cut-cycle time also includes change-out and place change times. The reasonableness of the methodology was validated by modeling an actual mining sequence and comparing results with time study and production report data collected from a cooperating mine over a two-week time period in which more than 300 cuts were mined. The validation effort also inspired some fine-tuning adjustments to the algorithm. In a case study application of the dynamic programming algorithm, a seven-day "optimal mining sequence" was identified for three crosscuts of advance on an eleven-entry super-section developing a main entry system for a new mine in southern Illinois. Productivity improvements attributable to the optimal sequence were marginal but the case study application reconfirmed the reasonableness of the methodology.
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13

Barban, Nicola. "Essays on sequence analysis for life course trajectories". Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3421549.

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The thesis is articulated in three chapters in which I explore methodological aspects of sequence analysis for life course studies and I present some empirical analyses. In the first chapter, I study the reliability of two holistic methods used in life-course methodology. Using simulated data, I compare the goodness of classification of Latent Class Analysis and Sequence Analysis techniques. I first compare the consistency of the classification obtained via the two techniques using an actual dataset on the life course trajectories of young adults. Then, I adopt a simulation approach to measure the ability of these two methods to correctly classify groups of life course trajectories when specific forms of “random” variability are introduced within pre-specified classes in an artificial datasets. In order to do so, I introduce simulation operators that have a life course and/or obser- vational meaning. In the second chapter, I propose a method to study the heterogeneity in life course trajectories. Using a non parametric approach, I evaluate the association between Optimal Matching distances and a set of categorical variables. Using data from the National Longitudinal Study of Adolescent Health (Add-Health), I study the hetero- geneity of early family trajectories in young women. In particular, I investigate if the OM distances can be partially explained by family characteristics and geographical context experienced during adolescence. The statistical methodology is a generalization of the analysis of variance (ANOVA) to any metric measure. In the last chapter, I present an application of sequence analysis. Using family transitions from Wave I to Wave IV of Add-health, I investigate the association between life trajectories and health outcomes at Wave IV. In particular, I am interested in exploring how differences in timing, quantum and order of family formation transitions are connected to self-reported health, depres- sion and risky behaviors in young women. Using lagged-value regression models, I take into account selection and the effect of confounding variables.
La tesi è articolata in tre sezioni distinte in cui vengono afffrontati sia aspetti metodologici che analisi empiriche riguardanti l’analisi delle sequenze per lo studio del corso di vita. Nel primo capitolo, viene presentato un confronto tra due metodi olistici per lo studio del corso di vita. Usando dati simulati, si confronta la bontà di classificazione ottenuta con modelli di classi latenti e tecniche di analisi delle sequenze. Le simulazioni sono effettuate introducendo errori di tipo stocastico in gruppi omogenei di traiettorie. Nel secondo capitolo, si propone di studiare l’eterogeneità nei percorsi di vita familiare. Usando un approccio nonparametrico, viene valutata l’associazione tra le distanze ottenute tramite l’algoritmo di Optimal Matching ed un insieme di variabili categoriche. Usando i dati provenienti dall’indagine National Longitudinal Study of Adolescent Health (Add-Health), si studia l’eterogeneità nei percorsi di formazione familiare di un campione di giovani donne statunitensi. La metodologia statistica proposta è una generalizzazione dell’analisi della varianza (ANOVA) . Nell’ultimo capitolo, si presenta un’applicazione dell’analisi delle sequenze per dati longitudinali. Usando i dati sulla transizione alla famiglia dalla prima alla quarta rilevazione nell’indagine Add-Health, vengono studiate le associazioni tra transizioni familiari e diversi indicatori di salute. In particolare, viene studiato come alcune caratteristiche legate alle transizioni familiari (timing, quantum, sequencing) siano associate allo stato generale di salute, depressione e comportamenti a rischio. La selezione e l’effetto di variabili confondenti sono prese in considerazione nell’analisi.
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14

Chen, Kanglin [Verfasser], Dirk [Akademischer Betreuer] Lorenz i Peter [Akademischer Betreuer] Maaß. "Optimal Control based Image Sequence Interpolation / Kanglin Chen. Gutachter: Dirk Lorenz ; Peter Maaß. Betreuer: Dirk Lorenz". Bremen : Staats- und Universitätsbibliothek Bremen, 2011. http://d-nb.info/1071898078/34.

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15

Arango, Nicolas(Nicolas S. ). "Sequence-phase optimal (SPO) [d̳e̳l̳t̳a̳]B₀ field control for lipid suppression and homogeneity for brain magnetic resonance spectroscopic imaging". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/128411.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, February, 2020
Cataloged from PDF version of thesis. [d̳e̳l̳t̳a̳] in title on title page appears as upper case Greek letter.
Includes bibliographical references (pages 33-35).
This work develops sequence-phase optimal (SPO) [delta]B₀ shimming methods to reduce lipid contamination and improve brain metabolite spectra in proton spectroscopic imaging. A rapidly reconfigurable 32-channel, local-multi-coil-shim-array is used to enhance lipid suppression and narrow metabolite linewidth in magnetic resonance spectroscopic imaging (MRSI) of the brain. The array is optimally reconfigured dynamically during each MRSI repetition period, first during the lipid-suppression phase, by widening the spectral gap between spatially separate lipid and metabolite regions, and then to narrow metabolite linewidth during readout, by brain-only [delta]B₀ homogenization. This sequence-phase-optimal (SPO) shimming approach is demonstrated on four volunteer subjects using a commercial 3T MRI outfitted with a 32-channel integrated RF receive and local multi-coil shim array. This proposed sequence-phase-optimal shimming significantly improves brain-metabolite MRSI in vivo, as measured by lipid suppression, brain metabolite chemical shift, and line widths. The time required to compute patient specific SPO shims negligibly impacted scan time. Sequence-phase-optimal shimming reduced lipid energy in the brain volume across four subjects by 88%, improved NAA FWHM by 23%, and dramatically reduced lipid ringing artifacts in quantified NAA and Glutamate metabolites, without increasing scan time or SAR.
by Nicolas Arango.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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16

Ngo, Thoi-Nhan. "Contrôle optimal en temps discret et en horizon infini". Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01E062/document.

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Cette thèse contient des contributions originales à la théorie du Contrôle Optimal en temps discret et en horizon infini du point de vue de Pontryagin. Il y a 5 chapitres dans cette thèse. Dans le chapitre 1, nous rappelons des résultats préliminaires sur les espaces de suites à valeur dans et des résultats de Calcul Différentiel. Dans le chapitre 2, nous étudions le problème de Contrôle Optimal, en temps discret et en horizon infini avec la contrainte asymptotique et avec le système autonome. En utilisant la structure d'espace affine de Banach de l'ensemble des suites convergentes vers 0, et la structure d'espace vectoriel de Banach de l'ensemble des suites bornées, nous traduisons ce problème en un problème d'optimisation statique dam des espaces de Banach. Après avoir établi des résultats originaux sur les opérateurs de Nemytskii sur les espaces de suites et après avoir adapté à notre problème un théorème d'existence de multiplicateurs, nous établissons un nouveau principe de Pontryagin faible pour notre problème. Dans le chapitre 3, nous établissons un principe de Pontryagin fort pour les problèmes considérés au chapitre 2 en utilisant un résultat de Ioffe-Tihomirov. Le chapitre 4 est consacré aux problèmes de Contrôle Optimal, en temps discret et en horizon infini, généraux avec plusieurs critères différents. La méthode utilisée est celle de la réduction à l'horizon fini, initiée par J. Blot et H. Chebbi en 2000. Les problèmes considérés sont gouvernés par des équations aux différences ou des inéquations aux différences. Un nouveau principe de Pontryagin faible est établi en utilisant un résultat récent de J. Blot sur les multiplicateurs à la Fritz John. Le chapitre 5 est consacré aux problèmes multicritères de Contrôle Optimal en temps discret et en horizon infini. De nouveaux principes de Pontryagin faibles et forts sont établis, là-aussi en utilisant des résultats récents d'optimisation, sous des hypothèses plus faibles que celles des résultats existants
This thesis contains original contributions to the optimal control theory in the discrete-time framework and in infinite horizon following the viewpoint of Pontryagin. There are 5 chapters in this thesis. In Chapter 1, we recall preliminary results on sequence spaces and on differential calculus in normed linear space. In Chapter 2, we study a single-objective optimal control problem in discrete-time framework and in infinite horizon with an asymptotic constraint and with autonomous system. We use an approach of functional analytic for this problem after translating it into the form of an optimization problem in Banach (sequence) spaces. Then a weak Pontyagin principle is established for this problem by using a classical multiplier rule in Banach spaces. In Chapter 3, we establish a strong Pontryagin principle for the problems considered in Chapter 2 using a result of Ioffe and Tihomirov. Chapter 4 is devoted to the problems of Optimal Control, in discrete time framework and in infinite horizon, which are more general with several different criteria. The used method is the reduction to finite-horizon initiated by J. Blot and H. Chebbi in 2000. The considered problems are governed by difference equations or difference inequations. A new weak Pontryagin principle is established using a recent result of J. Blot on the Fritz John multipliers. Chapter 5 deals with the multicriteria optimal control problems in discrete time framework and infinite horizon. New weak and strong Pontryagin principles are established, again using recent optimization results, under lighter assumptions than existing ones
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Nishijima, Yoshinori. "Effects of single-site and multi-site ventricular pacing on left and right ventricular mechanics and synchrony is there an optimal pacing sequence? /". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1126717344.

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Mahmud, Mohamed Taher Mustafa. "Optimal design and operation of multivessel batch distillation with fixed product demand. Modelling, simulation and optimisation of design and operation parameters in multivessel batch distillation under fixed product demand scenario and strict product specifications using simple dynamic model in gPROMS". Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4435.

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Increased interest in unconventional batch distillation column configurations offers new opportunities for increasing the flexibility and energy efficiency of batch distillation. One configuration of particular interest is multivessel batch distillation column, which can be viewed as a generalization of all previously studied batch column configuration. In this work, for the first time the optimal design and operation tasks are developed for multivessel batch distillation with strict product specifications under fixed product demand. Also, in this work, two different operation schemes defined as STN (State Task Network) in terms of the option and numbers of off-cuts were considered for binary and ternary separation. Both the vapour load and number of stages in each column section together with the production sequence are optimised to achieve maximum profit function. The performance of the multivessel batch distillation column is evaluated against the performance of conventional batch column with a simple dynamic model using binary and ternary mixtures. It has been found that profitability improves with the multivessel system in both separations. gPROMS, a user-friendly, software is used for the modeling, simulation, and optimisation.
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Mishra, Vishal Vijayshankar. "Sequence-to-Sequence Learning using Deep Learning for Optical Character Recognition (OCR)". University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513273051760905.

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Yasar, Temel Kaya. "Optimal Pulse Sequences for Magnetic Resonance Elastography". Thesis, University of Illinois at Chicago, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3668654.

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Magnetic Resonance Elastography (MRE) is a non-invasive phase contrast MR imaging method that captures the three-dimensional harmonic wave propagation introduced into subject by external actuators. This wave propagation vector field is processed into stiffness maps of various kinds that are used to assess the pathological changes that cannot be detected otherwise with non-invasive imaging methods. As in all other MR imaging methods, long acquisition duration is one of the important limiting factors for MRE. There are different approaches to reduce the scan time, such as reduced motion encoding MRE or fractional multi-frequency MRE; however, these methods are all at the cost of the reduced signal to noise ratio (SNR) or reduced phase to noise ratio (PNR). Recently we have introduced two accelerated MRE methods, which do not compromise SNR or PNR while reducing the acquisition time by a factor of three compared to the conventional MRE methods. The first one is Selective Spectral Displacement Projection (SDP) MRE method that can encode a mechanical motion of multiple frequency components at once. The second one is SampLe Interval Modulation (SLIM) MRE which can encode the mono-frequency motion in multiple directions concurrently. In this dissertation, I propose a final optimal method that integrates the technique developed in SLIM MRE into SDP MRE, namely Unified sampLing Time Interval ModulATion (ULTIMATe) MRE. This method is the optimal MRE method in the sense that it can reach the limit of time efficiency without sacrificing SNR and PNR. A new mathematical framework was introduced to accommodate all three methods while preventing any ambiguity which might otherwise can occur with the existing MRE notation.

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21

Andrews, Robert J. "Optical flow from color image sequences /". St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17830.pdf.

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Brujordet, Anders. "Finding an Optimal Approach for Indexing DNA Sequences". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11974.

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In this thesis you should find an optimal approach to index and retriev DNA sequences. As part of the task you should develop an algorithm that is fast, and accurate enough to find relevant sequences. The result will be evaluated based on speed, scalability and search efficiency (e.g. Precision and Recall). The approach should be implemented in a Java-based prototype which will be a "proof-of-the-concept".
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23

Fulton, John R. "Sensor orientation in image sequence analysis /". Connect to thesis, 2007. http://eprints.unimelb.edu.au/archive/00003510.

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Groussin, Mathieu. "Résurrection du passé à l’aide de modèles hétérogènes d’évolution des séquences protéiques". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10201/document.

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La reconstruction et la résurrection moléculaire de protéines ancestrales est au coeur de cette thèse. Alors que les données moléculaires fossiles sont quasi inexistantes, il est possible d'estimer quelles étaient les séquences ancestrales les plus probables le long d'un arbre phylogénétique décrivant les relations de parentés entre séquences actuelles. Avoir accès à ces séquences ancestrales permet alors de tester de nombreuses hypothèses biologiques, de la fonction des protéines ancestrales à l'adaptation des organismes à leur environnement. Cependant, ces inférences probabilistes de séquences ancestrales sont dépendantes de modèles de substitution fournissant les probabilités de changements entre acides aminés. Ces dernières années ont vu le développement de nouveaux modèles de substitutions d'acides aminés, permettant de mieux prendre en compte les phénomènes biologiques agissant sur l'évolution des séquences protéiques. Classiquement, les modèles supposent que le processus évolutif est à la fois le même pour tous les sites d'un alignement protéique et qu'il est resté constant au cours du temps lors de l'évolution des lignées. On parle alors de modèle homogène en temps et en sites. Les modèles récents, dits hétérogènes, ont alors permis de lever ces contraintes en permettant aux sites et/ou aux lignées d'évoluer selon différents processus. Durant cette thèse, de nouveaux modèles hétérogènes en temps et sites ont été développés en Maximum de Vraisemblance. Il a notamment été montré qu'ils permettent d'améliorer considérablement l'ajustement aux données et donc de mieux prendre en compte les phénomènes régissant l'évolution des séquences protéiques afin d'estimer de meilleurs séquences ancestrales. A l'aide de ces modèles et de reconstruction ou résurrection de protéines ancestrales en laboratoire, il a été montré que l'adaptation à la température est un déterminant majeur de la variation des taux évolutifs entre lignées d'Archées. De même, en appliquant ces modèles hétérogènes le long de l'arbre universel du vivant, il a été possible de mieux comprendre la nature du signal évolutif informant de manière non-parcimonieuse un ancêtre universel vivant à plus basse température que ses deux descendants, à savoir les ancêtres bactériens et archéens. Enfin, il a été montré que l'utilisation de tels modèles pouvait permettre d'améliorer la fonctionnalité des protéines ancestrales ressuscitées en laboratoire, ouvrant la voie à une meilleure compréhension des mécanismes évolutifs agissant sur les séquences biologiques
The molecular reconstruction and resurrection of ancestral proteins is the major issue tackled in this thesis manuscript. While fossil molecular data are almost nonexistent, phylogenetic methods allow to estimate what were the most likely ancestral protein sequences along a phylogenetic tree describing the relationships between extant sequences. With these ancestral sequences, several biological hypotheses can be tested, from the evolution of protein function to the inference of ancient environments in which the ancestors were adatapted. These probabilistic estimations of ancestral sequences depend on substitution models giving the different probabilities of substitution between all pairs of amino acids. Classicaly, substitution models assume in a simplistic way that the evolutionary process remains homogeneous (constant) among sites of the multiple sequence alignment or between lineages. During the last decade, several methodological improvements were realised, with the description of substitution models allowing to account for the heterogeneity of the process among sites and in time. During my thesis, I developed new heterogeneous substitution models in Maximum Likelihood that were proved to better fit the data than any other homogeneous or heterogeneous models. I also demonstrated their better performance regarding the accuracy of ancestral sequence reconstruction. With the use of these models to reconstruct or resurrect ancestral proteins, my coworkers and I showed the adapation to temperature is a major determinant of evolutionary rates in Archaea. Furthermore, we also deciphed the nature of the phylogenetic signal informing substitution models to infer a non-parsimonious scenario for the adaptation to temperature during early Life on Earth, with a non-hyperthermophilic last universal common ancestor living at lower temperatures than its two descendants. Finally, we showed that the use of heterogeneous models allow to improve the functionality of resurrected proteins, opening the way to a better understanding of evolutionary mechanisms acting on biological sequences
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25

Birger, Christopher. "Optimal Coherent Reconstruction of Unstructured Mesh Sequences with Evolving Topology". Thesis, Linköpings universitet, Medie- och Informationsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-112095.

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This thesis work will investigate and implement a method for reconstructing an unstructured mesh sequence with evolving topology. The goal of the method is to increase frame-to-frame coherency of the triangulation. The motivation of the method is that many of current state-of-the-art mesh compression and decimation algorithms for mesh sequences are based on static connectivity.
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26

Mustofadee, Affan. "Classification of muscles from ultrasound image sequences". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2391.

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The analysis of the health condition in Rheumatoid Arthritis (RA) remains a qualitative process dependent on visual inspection by a clinician. Fully automatic techniques that can accurately classify the health of the muscle have yet to be developed. The intended purpose of this work is to develop a novel spatio-temporal technique to assist in a rehabilitation program framework, by identifying motion features inherited in the muscles in order to classify them as either healthy or diseased. Experiments are based on ultrasound image sequences during which the muscles were undergoing contraction. The proposed system uses an optical flow technique to estimate the velocity of contraction. Analyzing and manipulating the velocity vectors reveal valuable information which encourages the extraction of motion features to discriminate the healthy against the sick. Experimental results for classification prove helpful in essential developments of therapy processes and the performance of the system has been validated by the cross-validation technique “leave-one-out”. The method leads to an analytical description of both the global and local muscle’s features in a way which enables the derivation of an appropriate strategy for classification. To our knowledge this is the first reported spatio-temporal method developed and evaluated for RA assessment. In addition, the progress of physical therapy to improve strength of muscles in RA patients has also been evaluated by the features used for classification.

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Lappas, Pelopidas. "Optimal motion estimation of features and objects in long image sequences". Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/265064/.

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Verlet, Jan Raf Rogier. "Controlling electronic and molecular dynamics using optical pulse sequences". Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397922.

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Buratto, Steven Keith Weitekamp Daniel P. "Time-sequenced optical nuclear magnetic resonance of gallium arsenide /". Diss., Pasadena, Calif. : California Institute of Technology, 1993. http://resolver.caltech.edu/CaltechETD:etd-11092004-164546.

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Cho, Jin Woo. "Advanced optical receivers using cross layer optimization and maximum-likelihood sequence detection /". May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Dunning, Alexander. "Coherent atomic manipulation and cooling using composite optical pulse sequences". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/364735/.

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The laser cooling of atoms to ultracold temperatures has propelled many groundbreaking advances in fundamental research and precision measurement, through such applications as quantum simulators and interferometric sensors. Laser cooling remains, however, highly species-selective, and techniques for its application to molecules are still in their infancy. This thesis broadly concerns the development of laser cooling schemes, based on sequences of coherent optical pulses, which can in principle be applied to a wide range of species. We describe a cooling scheme, in which a velocity-selective impulse analogous to that in Doppler cooling is generated by a light-pulse Ramsey interferometer, and present a proof-of-concept demonstration of the scheme using ultracold rubidium-85 atoms as a test-bed. We realise an interferometer for the atoms, as they are in free-fall after release from a magneto-optical trap, by inducing stimulated Raman transitions between their ground hyperfine states. We provide a comprehensive characterisation of these Raman light-pulse interferometer optics, where particular attention is paid to light shift effects. Raman pulses, and indeed coherent operations in any quantum control system, unavoidably suffer from systematic errors in the control field intensity and frequency, and these lead to reductions in pulse fidelity and readout contrast. In parallel to the work on interferometric cooling in this thesis, we report our preliminary investigations into composite pulses, whereby `naive' single pulses are replaced by sequences of rotations with tailored durations and phases, for improving pulse fidelity in the presence of inhomogeneities. We find that composite pulses can indeed be highly effective in our cold atom system, and propose that their application in such devices as interferometric sensors is a promising prospect.
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32

Reysset, Aurelien. "Conception préliminaire d'actionneurs électromécaniques - outils d'aide à la spécification et à la génération de procédures de dimensionnement pour l'optimisation". Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0003/document.

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Cette thèse a pour objectif d’apporter un ensemble d’outils logiciels s’inscrivant dans une méthodologie globale de conception de systèmes mécatroniques. Elle arrive en complément de travaux déjà menés au sein du laboratoire sur le pré-dimensionnement d’actionneurs aéronautiques de nouvelle génération : les actionneurs électromécaniques (EMA). Cette technologie apporte de nouvelles problématiques qui forcent les ingénieurs à modifier leur processus de développement et ce dès la phase de spécification où des profils de mission devront être générés/transformés/analysés de manière à simplifier la conception et assurer leur validation. Une toolbox Simulink a donc été créée dans cette thèse pour répondre à ce besoin de transformation de l’information entre avionneur et systémier. Comme tout système embarqué, le concepteur fait face à des compromis entre performances, durée de vie et intégration, qui peuvent se résumer à un problème d’optimisation décrit par un ensemble d’équations et de contraintes. Un effort particulier de description a été mené sur le conditionnement de ces équations sous la forme d’un séquencement de calculs explicites adaptés aux algorithmes d’optimisation. La méthode et son implémentation logicielle, toutes deux basées sur la théorie des graphes, interagissent avec le concepteur de manière à l’informer des erreurs de singularité ou de bouclages algébriques apparaissant dans son problème et à lui fournir des pistes de résolution. Pour finir, des études de pré-dimensionnement d’actionneurs de train d’atterrissage et de surfaces de vol primaires (aileron et spoiler), réalisées dans le cadre de cette thèse, dresseront les possibilités offertes par cette approche innovante : conception intégrée avec une cinématique complexe, conception collaborative pluri-partenaires découplée, utilisation de surfaces de réponse pour accélérer l’optimisation
The aim of this thesis is to bring a package of software tools included in a whole methodology dealing with mechatronic systems design. It comes as an add-on to the work already carried out at the laboratory in the field of the new generation of aircraft actuation systems: electromechanical actuators (EMA). This technology triggers new problematics leading the engineers to modify their development process as early as the specification phase, when mission profiles have to be generated/transformed/analyzed in order to simplify the design and ensure the validation step. Thus a Simulink toolbox has been created to meet the need for an information translator working as an intermediate between airframer and system-supplier. As for all the embedded systems, the designer has to face some performance-lifetime-integration trade-off, which can be considered as an optimization problem described by a set of equations and constraints. Particular attention is paid here to the conditioning of those explicit equations in order to obtain a standardized calculation sequence adapted to many optimization algorithms. The method and implemented software, both based on the graph theory, interact with the designer to inform him on the possible singularity and algebraic loop issues, providing some leads for their resolution. Finally, some preliminary sizing studies of landing gear and primary flight control surfaces (aileron and spoiler) actuation systems are presented to highlight the possibilities brought out by this innovative approach: integrated design with complex kinematics, collaborative multi-partners design, use of response surfaces to speed up the optimization
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Bir, Amarpreet Singh. "Optimum stacking sequence design of composite sandwich panel using genetic algorithms". California State University, Long Beach, 2013.

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Weld, Andrew Mark. "Optical diffraction-based silicon sensors for the detection of DNA sequences". Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/47762/.

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This thesis describes the design, fabrication and characterisation of diffraction-based sensors on silicon (100) substrates for the detection of complementary DNA sequences using colloidal gold labels. In-depth analysis of variations of DNA sequence within the human genome and association with diseases is expected to lead to personalised medical treatment. There is a great need for DNA analysis technologies and for techniques to determine whether sequence variations occur on the same chromosomal strand with applications in disease screening and diagnosis. Novel two-dimensional diffraction structures are designed and fabricated. It is shown that two-dimensional diffraction approaches may potentially offer multiplexing of DNA detection assays.
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35

Lee, Rebekah Ann. "Assembly, Annotation and Optical Mapping of the A Subgenome of Avena". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7238.

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Common oat (Avena) has held a significant place within the global crop community for centuries; although its cultivation has decreased over the past century, its nutritional benefits have recently garnered increased interest for human consumption. No published reference sequences are available for any of the three oat subgenomes. Here we report a quality sequence assembly, annotation and hybrid optical map of the A-genome diploid Avena atlantica Baum and Fedak. The assembly is composed of a total of 3,417 contigs with an N50 of 11.86 Mb and an estimated completeness of 97.6%. This genome sequence will be a valuable research tool within the oat community.
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Zapata, Iván R. "Detecting humans in video sequences using statistical color and shape models". [Gainesville, Fla.] : University of Florida, 2001. http://etd.fcla.edu/etd/uf/2001/anp1058/ivan%5Fthesis2.pdf.

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Thesis (M.S.)--University of Florida, 2001.
Title from first page of PDF file. Document formatted into pages; contains viii, 49 p.; also contains graphics. Vita. Includes bibliographical references (p. 47-48).
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Wang, Yunmiao. "Microgap Structured Optical Sensor for Fast Label-free DNA Detection". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32875.

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DNA detection technology has developed rapidly due to its extensive application in clinical diagnostics, bioengineering, environmental monitoring, and food science areas. Currently developed methods such as surface Plasmon resonance (SPR) methods, fluorescent dye labeled methods and electrochemical methods, usually have the problems of bulky size, high equipment cost and time-consuming algorithms, so limiting their application for in vivo detection. In this work, an intrinsic Fabry-Perot interferometric (IFPI) based DNA sensor is presented with the intrinsic advantages of small size, low cost and corrosion-tolerance. This sensor has experimentally demonstrated its high sensitivity and selectivity. In theory, DNA detection is realized by interrogating the sensorâ s optical cavity length variation resulting from hybridization event. First, a microgap structure based IFPI sensor is fabricated with simple etching and splicing technology. Subsequently, considering the sugar phosphate backbone of DNA, layer-by-layer electrostatic self-assembly technique is adopted to attach the single strand capture DNA to the sensor endface. When the target DNA strand binds to the single-stranded DNA successfully, the optical cavity length of sensor will be increased. Finally, by demodulating the sensor spectrum, DNA hybridization event can be judged qualitatively. This sensor can realize DNA detection without attached label, which save the experiment expense and time. Also the hybridization detection is finished within a few minutes. This quick response feature makes it more attractive in diagnose application. Since the sensitivity and specificity are the most widely used statistics to describe a diagnostic test, so these characteristics are used to evaluate this biosensor. Experimental results demonstrate that this sensor has a sensitivity of 6nmol/ml and can identify a 2 bp mismatch. Since this sensor is optical fiber based, it has robust structure and small size ( 125μm ). If extra etching process is applied to the sensor, the size can be further reduced. This promises the sensor potential application of in-cell detection. Further investigation can be focused on the nanofabrication of this DNA sensor, and this is very meaningful topic not only for diagnostic test but also in many other applications such as food industry, environment monitoring.
Master of Science
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38

Boukebeche, Djemaa. "Resultats limites presque surs optimaux des k-espacements pour une loi uniforme". Paris 6, 1988. http://www.theses.fr/1988PA066096.

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Soit x::(1),x::(2) une suite de variables aeatoires i. I. D. De fonction de densite f positive sur (a,b) et nulle ailleurs. On etudie le comportement asymptotique quand n->infini du maximum des k-espacements m::(n)**(k) induit par la statistique d'ordre de x::(1),x::(2). . . X::(n)
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Luo, Ying. "Statistical semantic analysis of spatio-temporal image sequences /". Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/5884.

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Corvee, Etienne. "Investigating optical flow and tracking techniques for recovering motion within image sequences". Thesis, Kingston University, 2005. http://eprints.kingston.ac.uk/20293/.

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Analysing objects interacting in a 3D environment and captured by a video camera requires knowledge of their motions. Motion estimation provides such information, and consists of re-covering 2D image velocity, or optical flow, of the corresponding moving 3D objects. A gradient-based optical flow estimator is implemented in this thesis to produce a dense field of velocity vectors across an image. An iterative and parameterised approach is adopted which fits planar motion models locally on the image plane. Motion is then estimated using a least-squares minimisation approach. The possible approximations of the optical flow derivative are shown to differ greatly when the magnitude of the motion increases. However, the widely used derivative term remains the optimal approximation to use in the range of accuracies of the gradient-based estimators i.e. small motion magnitudes. Gradient-based estimators do not estimate motion robustly when noise, large motions and multiple motions are present across object boundaries. A robust statistical and multi-resolution estimator is developed in this study to address these limitations. Despite significant improvement in performance, the multiple motion problem remains a major limitation. A confidence measurement is designed around optical flow covariance to represent motion accuracy, and is shown to visually represent the lack of robustness across motion boundaries. The recent hyperplane technique is also studied as a global motion estimator but proved unreliable compared to the gradient-based approach. A computationally expensive optical flow estimator is then designed for the purpose of detecting at frame-rate moving objects occluding background scenes which are composed of static objects captured by moving pan and tilt cameras. This was achieved by adapting the estimator to perform global motion estimation i.e. estimating the motion of the background scenes. Moving objects are segmented from a thresholding operation on the grey-level differences between motion compensated background frames and captured frames. Filtering operations on small object dimensions and using moving edge information produced reliable results with small levels of noise. The issue of tracking moving objects is studied with the specific problem of data correspondence in occlusion scenarios.
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Anderson, Curtis James. "Estimating the Optimal Extrapolation Parameter for Extrapolated Iterative Methods When Solving Sequences of Linear Systems". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1383826559.

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Stanley, Michael Clare. "A quantitative estimation of the value of geoscience information in mineral exploration: Optimal search sequences". Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186863.

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This research provides quantitative estimates of value of geoscience information in the exploration for porphyry copper deposits of Arizona. As part of the study, an expert system named DISCOVERY is designed to integrate geological models, statistical decision theory, and mineral economics within a Monte Carlo simulation framework. The system requires, for each exploration survey, a probability that a simulated deposit will be detected. These detection probabilities are estimated using expert opinion from a panel of experienced geoscientists. This dissertation pioneers the application of influence allocation processes in geoscience, to alleviate criticisms associated with expert opinion. The work has five major focuses: (1) an adaptation of Grayson's (1960) exploration decision theory into a modified Bayesian framework; (2) the use of electronic brainstorming to define principal recognition features that define exploration deposit models; (3) the use of influence allocation voting tools to estimate detection probability by survey type and sampling intensity; (4) a comprehensive engineering cost model to derive the net present value of deposits simulated within the system; and (5) a comprehensive drilling model to describe optimal sampling intensity in regional exploration. The system operates using two models: (1) an estimate of the value of information based upon 'static' estimates; and (2) a 'dynamic' simulation model that replicates the activities of the exploration industry. The static model provides value estimates on a survey by survey basis, consistent with prevailing economic conditions. The dynamic model loosens the economic constraints in order to simulate exploration practices and determine the optimal sequence of search surveys. Collectively these two models provide estimates of the value of information derived from exploration surveys and determine the optimum search strategy for porphyry copper deposits in Arizona. The static model produces estimates of net gain displaying a high level of consistency for each survey technology and sampling intensity across many thousands of iterations. The dynamic model does not produce satisfying results, requiring additional modifications to the Bayesian structure in order to better simulate exploration.
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43

Aue, Volker. "Optimum linear single user detection in direct-sequence spread-spectrum multiple access systems". Thesis, Virginia Tech, 1995. http://hdl.handle.net/10919/43609.

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After Qualcomm's proposal of the IS-95 standard, code-division multiple access (CDMA) gained popularity as an alternative multiple-access scheme in cellular and personal communication systems (PCS). Besides the advantage of allowing asynchronous operation of the users, CDMA direct-sequence spread spectrum (DS-SS) offers resistance to frequency selective fading and graceful degradation of the performance as the number of users increases.

Orthogonality of the signals in time-division multiple access and frequency-division multiple access is inherent from the nature of the multiple access scheme. In a CDMA system, orthogonality of the signals is not guaranteed in general. Consequently, the performance of conventional correlation receivers suffers.

Sub-optimum receivers which use knowledge of the interfering signals have been investigated by other researchers. These receivers attempt to cancel the multi-user interference by despreading the interfering users. Hence, these receivers require knowledge about all the spreading codes, amplitude levels, and signal timing, and are, in general, computationally intensive.

In this thesis, a technique is presented for which a high degree of interference rejection can be obtained without the necessity of despreading each user. It is shown that exploiting spectral correlation can help mitigate the effects of the multiple-access interference. If code-on-pulse DS-SS modulation is used, a cyclic form of the Wiener filter provides substantial improvements in performance in terms of bit error rate and user capacity. Furthermore, it is shown, that a special error-criterion should be used to adapt the weights of the filter.

The computational complexity of the receiver is equivalent to that of conventional equalizers.


Master of Science
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44

Jie, Cao, i Xie Qiu-cheng. "THE SEARCHING METHOD OF QUASI-OPTIMUM GROUP SYNC CODES ON THE SUBSET OF PN SEQUENCES". International Foundation for Telemetering, 1990. http://hdl.handle.net/10150/613438.

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International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada
As the code length is increasing, the search of optimum group sync codes will be more and more difficult, even impossible. This paper gives the searching method of quasi-optimum group sync codes on the small subset of PN sequences -- CVT-TAIL SEARCHING METHOD and PREFIX-SUFFIX SEARCHING METHOD. We have searched out quasi-optimum group sync codes for their lengths N=32-63 by this method and compared them with corresponding optimum group sync codes for their lengths N=32-54. They are very approximative. The total searching time is only several seconds. This method may solves the problems among error sync probability, code length and searching time. So, it is a good and practicable searching method for long code.
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45

Sergison, Darryl James. "Untangling the signals : investigating accretion and photometric variability in young stars". Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18720.

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In this thesis, an assessment is made of the value of optical CMDs as a useful diagnostic of the accretion properties of young stars. An analysis has been made of the phenomena that we observe and their effect on the position of stars in the CMD. Limitations and potential biases have been identified and evaluated. Variability causes some luminosity spread at a given colour in optical CMDs. A detailed characterisation of variability has been performed which places strong constraints on the magnitudes and the timescales on which the variability is seen. On timescales 15 minutes, almost no variability is detected (at levels greater than ≈ 0.2%) in the i band for a sample of ≈ 700 disc-bearing young stellar objects (YSOs). This suggests that the variability predicted by some accretion shock models is either very weak or not present. On hours to days timescales the optical variability in most stars is well described by a simple power law. The amplitude of the variability, a ∝ f−k, where f is the frequency of the variability in days. Disc-bearing and discless YSOs exhibit median values of k of 0.85 ± 0.02 and 0.95 ± 0.03 respectively, the uncertainity being the error on the median. The power law is valid up to a certain timescale (tmax) at which point the variability amplitude does not increase any further. tmax is found to be 1.50 ± 0.07 days and 1.41 ± 0.10 days for disc-bearing and discless stars respectively. Disc-bearing stars show greater variability amplitudes than the discless stars. However, it is notable that the variability timescale and power spectrum exponent are remarkably similar. This implies that the amplitude of the variability is driven by the physics of the underlying process, but that the timescales are instead driven by geometric effects. For disc-bearing stars, the highest amplitude variables are the accreting stars, which often appear to vary in the CMD along lines that correspond to changes in accretion luminosity. Four disc-bearing stars (approximately 0.5% of the disc-bearing sample) in Cep OB3b show extreme variability on timescales of years. Three (possible EXor candidates), show long-timescale changes that have a dramatic effect on their CMD position. However their small numbers mean that the overall impact on the CMDs of young associations is small. Variability on timescales of the rotational period and shorter adds uncertainty to age estimates of individual stars that are calculated by comparison with PMS models. Having provided a detailed description of variability and its impact on the CMD, it is clear that there are further significant mechanisms that affect the positions of YSOs in the CMD. I show that the spread in luminosity seen in the Orion Nebula Cluster and NGC 2264 could not be explained by accretion at rates of M ̇ ≥ 5 × 10−4 M⊙ yr−1 occurring within the protostellar phase of YSO evolution. Thus it appears that CMDs are not a useful diagnostic for study of the accretion histories of YSOs. The wavelength dependence of the extinction by dust within the inner regions of YSO discs is shown to differ from that seen in the ISM. Typically the wavelength dependence of the extinction is given by RV ≈5-8, compared with the value of RV ≈3.1 typical of the ISM. The interpretation is that grain growth has occurred. The location of this material within the ‘snow line’ implies that grains have coalesced rather than simply gaining an ice mantle. This is evidence for the beginning of planet formation. The effect of the high value of RV on the CMD is to add additional uncertainty of 0.1 mag to photometric measurements that have been corrected for the effects of extinction. Accretion luminosity is shown to be the dominant signal in the luminosity spread seen in CMDs of young associations. Stars which exhibit excess flux in the U band or Hα are displaced in CMD space. The accretion vector is shown to be a significant blueward shift in colour accompa- nied by a modest brightening in the g, g − i CMD. Accretion results in a luminosity spread as stars are displaced blueward below the PMS locus. This effect is not seen in non-accreting disc-bearing stars. Examination of the underlying excess luminosity spectrum for 15 accreting stars shows that the colour of the emission excess is not consistent across the sample. Thus to quantify the effect of accretion luminosity on CMD positions for individual stars, moderate resolution spectra are required with a large range in wavelength. This accretion luminosity may systematically bias estimates of PMS ages. A simple mitigation is to exclude accreting stars from age analysis. U band and Hα flux excesses are shown to vary independently by ≈ 1 dex on timescales shorter than the rotation period of the star. The relation between U band flux excess and veiling at 7000Å also appears to be variable. This implies that single epoch measurements of these parameters will add an uncertainty of ≈ 1 dex on accretion rates derived from them. Accretion rates derived from either U or Hα excess should be calculated from a mean of several photometric measurements, separated by significant fractions of the rotation period of the star. In most stars, the veiling at 7000Å is shown not to be a good measure for the calculation of the accretion rate. Despite providing a detailed characterisation of phenomena that influence the positions of YSOs in the CMD, there exists some residual luminosity spread at a given Teff that cannot be explained by variability on any timescale, extinction uncertainties or accretion luminosity. This residual spread should provide an opportunity to study an as-yet uncharacterised aspect of young stars.
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46

Costa, Camila Ferreira. "Nearest Neighbors with Operating Time Constraints and Optimal Sequenced Route Queries in Time-Dependent Road Networks". reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/13358.

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COSTA, C. F. Nearest Neighbors with Operating Time Constraints and Optimal Sequenced Route Queries in Time-Dependent Road Networks. 2014. 75 f. Dissertação (Mestrado em Ciência da Computação) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2014.
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In this thesis we study the problems of processing a variation of nearest neighbors and of routing planning queries in time-dependent road networks, i.e., one where travel time along each edge is a function of the departure time. We first study the problem of finding the k points of interest (POIs), for example, museums or restaurants, in which a user can start to be served in the minimum amount of time, accounting for both the travel time to the POI and the waiting time there, if it is closed. Previous works have proposed solutions to answer k-nearest neighbor queries considering the time dependency of the network but not the operating times of the points of interest. We propose and discuss three solutions to this type of query which are based on the previously proposed incremental network expansion and use the A* search algorithm equipped with suitable heuristic functions. We also present experimental results comparing the number of disk access required in each solution with respect to a few different parameters. In the second query, we aim at finding the optimal route that connects a origin to a destination and passes through a number of POIs in a specific sequence imposed on the categories of the POIs. Previous works have addressed this problem, but they do not consider the time dependency of the network. We propose an optimal sequenced route query algorithm which performs an incremental network expansion adopting an A* search. Furthermore, as an OSR query on road network tends to re-expand an extremely large number of nodes, we propose a scheme to reduce the re-expansions. For comparison purposes, we also present a baseline solution which was obtained by extending the previously proposed progressive neighbor exploration algorithm to cope with the time-dependent problem. We performed experiments in synthetic networks comparing the proposed solutions according to the number of expanded vertices in the search and the processing time of the queries.
Nesta dissertação nós estudamos os problemas de processar uma variação de consulta de vizinhos mais próximos e de planejamento de rotas em redes viárias dependentes do tempo. Diferentemente de redes convencionais, onde o custo de deslocamento de um ponto a outro é geralmente dado pela distância física entre esses dois pontos, uma rede dependente do tempo representa de forma mais realista o custo de realizar esse deslocamento, considerando o histórico das condições de tráfego. Mais especificamente, o tempo que um objeto móvel leva para percorrer uma via em tal rede depende do tempo de partida. Por exemplo, o tempo para se deslocar de um ponto a outro em grandes centros durante os horários de pico, quando o tráfego é intenso e as ruas estão congestionadas, é muito maior do que em horários normais. Dentro do contexto apresentado, primeiramente nós estudamos o problema de encontrar k pontos de interesse, como por exemplo, museus ou restaurantes, nos quais um usuário pode começar a ser servido o mais rápido possível. Em outras palavras, nós buscamos minimizar a soma do tempo de viagem até um ponto de interesse mais o tempo de espera até que ele abra, caso esteja fechado. Trabalhos anteriores tratam do problema de encontrar os k vizinhos mais próximos em redes dependentes do tempo, porém, eles não levam em consideração o horário de funcionamento dos pontos de interesse. Desta forma, a consulta abordada nesses trabalhos pode retornar pontos de interesse que estão mais próximos do usuário, considerando um dado tempo de partida, mas que podem demorar para abrir, fazendo com que o usuário espere por muito tempo. Nós propomos e discutimos três soluções para essa consulta que são baseadas em um algoritmo de expansão incremental da rede previamente proposto na literatura e usam o algoritmo de busca A* equipado com funções heurísticas adequadas para cada solução. Com o uso do algoritmo A*, nós visamos reduzir o percentual da rede avaliado na busca, evitando expandir vértices que oferecem uma baixa probabilidade de alcançar nosso objetivo. Também apresentamos resultados experimentais que comparam o número de acessos ao disco exigido em cada solução em relação a alguns parâmetros diferentes e que indicam em que casos deve-se optar por cada solução. Na segunda consulta, nós visamos encontrar a rota ótima que conecta uma dada origem a um dado destino e que passa por uma série de pontos de interesse pertencentes a categorias determinadas pelo usuário em uma certa ordem também especificada pelo usuário. Esse tipo de consulta é conhecida como OSR, do inglês, Optimal Sequenced Route, na literatura. Como exemplo, considere que alguém está indo do trabalho para casa e no seu caminho deseja passar em um banco para sacar dinheiro e depois ir a um restaurante para jantar. Embora existam vários bancos e restaurantes em uma cidade, uma consulta OSR deve procurar pelo banco e pelo restaurante que minimizam o custo da viagem do trabalho para casa. Trabalhos anteriores propuseram soluções para consultas OSR em redes com arestas de custo fixo, mas nenhum deles considerou que esse custo pode variar de acordo com o tempo de partida. Nós propomos uma solução ótima para esse problema que, assim como as abordagens propostas para o problema anterior, expande a rede incrementalmente e usa o algoritmo A* para guiar essa expansão. Além disso, como uma consulta OSR em redes viárias tende a re-expandir um número muito grande de vértices, nós incorporamos à essa solução um esquema para reduzir o número de re-expansões. Nós também apresentamos resultados experimentais que mostram a eficiência dessa solução em comparação com uma solução de base que foi obtida a partir da estensão de um algoritmo anteriormente proposto na literatura. Todos os experimentos foram realizados em redes sintéticas.
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47

Masi, Marco. "Modeling of sequences of Silicon micro-Resonators for On-Chip Optical Routing and Switching". Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/369141.

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The purpose of this thesis is to focus on the aspect of passive devices allowing for WDM, routing, switching and filtering of optical signals, investigating novel routing concepts based on micro optical side coupled resonators to achieve large bandwidth by multiple cascading and/or multiple coupling (low group velocity) periodicity effects. We will describe some technical aspects necessary for the design and fabrication of some passive circuitry, and usually neglected in purely theoretical approaches, including optical routers based on racetrack resonators and novel SCISSOR and CROW devices.
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48

Masi, Marco. "Modeling of sequences of Silicon micro-Resonators for On-Chip Optical Routing and Switching". Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/462/1/Tesi_finale.pdf.

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The purpose of this thesis is to focus on the aspect of passive devices allowing for WDM, routing, switching and filtering of optical signals, investigating novel routing concepts based on micro optical side coupled resonators to achieve large bandwidth by multiple cascading and/or multiple coupling (low group velocity) periodicity effects. We will describe some technical aspects necessary for the design and fabrication of some passive circuitry, and usually neglected in purely theoretical approaches, including optical routers based on racetrack resonators and novel SCISSOR and CROW devices.
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49

Feuillâtre, Hélène. "Détermination automatique de l'incidence optimale pour l'observation des lésions coronaires en imagerie rotationnelle R-X". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S039/document.

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Les travaux de cette thèse s’inscrivent dans le cadre du planning de traitements minimalement invasifs des lésions des artères coronaires. Le cardiologue réalise un examen coronarographique, puis dans la continuité, une angioplastie transluminale. L’angiographie rotationnelle à rayons X permet de visualiser sous différentes incidences 2D la lumière des artères coronaires sur plusieurs cycles cardiaques et aussi d’obtenir une reconstruction 3D+T des arbres coronaires. A partir de cette séquence, notre objectif est de déterminer automatiquement une incidence optimale 2D du segment sténosé compatible avec les angles du C-arm afin d’aider le cardiologue lors de l’intervention.Différentes étapes sont considérées pour calculer la position angulaire optimale du C-arm. Afin de suivre la zone de lésion durant le cycle cardiaque, une première méthode est proposée pour mettre en correspondance tous les arbres de la séquence 3D+T. Tout d’abord, un appariement deux à deux des arbres successifs est réalisé afin de construire un arbre d’union. Ces derniers sont ensuite fusionnés afin d’obtenir un arbre mosaïque représentant l’arbre le plus complet de la séquence. L’utilisation de mesures de similarités géométriques et hiérarchiques ainsi que l’insertion de nœuds artificiels permet de prendre en compte les différents mouvements non-rigides des artères coronaires subits au cours du cycle cardiaque et les variations topologiques dû à leurs extractions. Cet appariement nous permet de proposer une deuxième méthode afin d’obtenir une vue angiographique 2D optimale de la zone de lésion tout le long du cycle cardiaque. Cette incidence est proposée spécifiquement pour trois types de région d’intérêt (segment unique, segment multiple ou bifurcation) et est calculée à partir de quatre critères (raccourcissement, chevauchement interne et externe ou angle d’ouverture de bifurcation). Une vue 2D déployée du segment projeté avec le moins de superposition avec les structures vasculaires avoisinantes est obtenue. Nous donnons également la possibilité au cardiologue d’avoir une incidence optimale privilégiant soit le déploiement du stent ou soit le guidage d’outils de la racine de l’arbre à la zone sténosée. Nos différents algorithmes ont été évalués sur une séquence réelle de 10 phases segmentées à partir d’un CT et de 41 séquences simulées
The thesis work deals with the planning of minimally invasive surgery of coronary artery lesions. The physician performs a coronarography following by a percutaneous transluminal angioplasty. The X-ray rotational angiography permits to visualize the lumen artery under different projection angles in several cardiac cycles. From these 2D projections, a 3D+T reconstruction of coronary arteries can be obtained. Our goal is to determine automatically from this 3D+T sequence, the optimal angiographic viewing angle of the stenotic segment. Several steps are proposed to compute the optimal angular position of the C-arm. Firstly, a mosaic-based tree matching algorithm of the 3D+T sequence is proposed to follow the stenotic lesion in the whole cardiac cycle. A pair-wise inexact tree matching is performed to build a tree union between successive trees. Next, these union trees are merged to obtain the mosaic tree which represents the most complete tree of the sequence. To take into account the non-rigid movement of coronary arteries during the cardiac cycle and their topology variations due to the 3D reconstruction or segmentation, similarity measures based on hierarchical and geometrical features are used. Artificial nodes are also inserted. With this global tree sequence matching, we propose secondly a new method to determine the optimal viewing angle of the stenotic lesion throughout the cardiac cycle. This 2D angiographic view which is proposed for three regions of interest (single segment, multiple segment or bifurcation) is computed from four criteria: the foreshortening, the external and internal overlap and the bifurcation opening angle rates. The optimal view shows the segment in its most extended and unobstructed dimension. This 2D view can be optimal either for the deployment of the stent or for the catheter guidance (from the root to the lesion). Our different algorithms are evaluated on real sequence (CT segmentation) and 41 simulated sequences
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50

Karlsson, Fredrik. "Matting of Natural Image Sequences using Bayesian Statistics". Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2355.

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The problem of separating a non-rectangular foreground image from a background image is a classical problem in image processing and analysis, known as matting or keying. A common example is a film frame where an actor is extracted from the background to later be placed on a different background. Compositing of these objects against a new background is one of the most common operations in the creation of visual effects. When the original background is of non-constant color the matting becomes an under determined problem, for which a unique solution cannot be found.

This thesis describes a framework for computing mattes from images with backgrounds of non-constant color, using Bayesian statistics. Foreground and background color distributions are modeled as oriented Gaussians and optimal color and opacity values are determined using a maximum a posteriori approach. Together with information from optical flow algorithms, the framework produces mattes for image sequences without needing user input for each frame.

The approach used in this thesis differs from previous research in a few areas. The optimal order of processing is determined in a different way and sampling of color values is changed to work more efficiently on high-resolution images. Finally a gradient-guided local smoothness constraint can optionally be used to improve results for cases where the normal technique produces poor results.

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